Electronic tube



April 17, 1945. i w. EI"I:E L ET AL ELECTRONIC, TUBE Filed July 21, 19422 Sheets-Sheet 1 H L6 5% m5 wmw mMm m4 L w a Y B THEIR ATTORNEY April1945- w. w. EITEL ET AL 7 2,373,950 ELECTRONIC TUBE Filed July 21, 19422 Sheets-Sheet 2 u mmrm'n INVE NTOR5 v WILL/AM W. E/TEL UACK A.MCULLOU6HMEJ THEIR ATTORNEY Patented Apr. 17, 1945 "UNITE-D STATES PATENT oi-FloELECTRONIC TUBE William W. Eitel, San Bruno, and Jack A.

McCullough, Millbrae, Calif., assignors to Eitel- McCullough, Inc., SanBruno, Calif., a corporav tion of California Application July 21, 1942,Serial No. 451,800

3'Claims. (or. 250-275) going, are set forth in the followingdescription of our invention. It is to be understood that we do notlimit ourselves to this disclosure of species of our invention, as wemay adopt variant em-' bodiments thereof within the scope of the claims.

Referring to the drawings: Figure l is a perspective view of a tubeembodying the improvements of our invention; and

Figure 2 is a side view of the same, partly in section and partly inelevation.

In terms of broad inclusion, our tube comprises an envelope enclosing aplurality of electrodes and having leads therefore sealed to theenvelope. A shield is disposed transversely of the envelope between itsstem end and the electrodes, which shield is supported on certain of theelectrode leads. The envelope preferably contains a plurality ofoperative units, each including a cathode and grid and plate, and theshield is preferably supported on the. grid leads.

In greater detail, and referring to the drawings,

our tube comprises an envelope of glass or the like having a cylindricalbody with an enlarged portion 2 and a reduced portion 3. portion isjoined to a neck 4 at a shoulder forming a flat ledge 6 between theseparts. A reentrant stem 1 projects inwardly from the lower end of neck4. The tube is fitted with a suitable base 8 carrying prongs 9. I

Within the envelope are arranged a plurality of operative units, sayfour triode units, each including a filamentary cathode ll, grid l2 anda capped plate I3. These units are disposed about parallel axes and areequally spaced about the axis of the envelope. The plate electrodes areunitarily supported by a bracket 14 on a common plate lead l6 extendingthru the top of the envelope at seal ll. Cathodes ll each have a pair ofleads 18, all sealed to stem 1'; these leads being connected to prongs 9so that two of the filaments are connected in parallel to a pair of Thelatter 1 the prongs and the other two filaments in parallel to the othertwo prongs.

Grids H are separately supported on the upper .ends of leads 2! bybrackets 22. These grid leads extend longitudinally of the envelope andare equally spaced about the tube axis in alignment with the electrodes.The lower ends of leads 2| project thru ledge 6 of the envelope at seals23, and are Welded to lips 24 on a common external terminal ring 26cemented to the envelope at the shoulder. A projection 21 on the ringprovides a terminal button.

We also provide improved means in the envelope for shielding stem 1 andgrid lead seals 23 against heat and electron bombardment from theelectrodes.

lead seals, at which points the glass is strained and particularly proneto crack under excessive heating. V

This difiiculty is overcome in our tube by means of a circular shield28, preferably of nickel, disposed transversely of the envelope betweenthe stem and the electrodes. Apertures 29 in the shield provide freepassage forthe cathode leads. The shield is supported on grid leads 2|by means of tabs 3| welded to the leads.

In order to give full protection to the stem and seals, shield 28 issubstantially co-extensive with the cross-sectional area of theenvelope; the shield periphery terminating adjacent the annular sidewall of the envelope. The shield is preferably cup-shaped with its sideflange. 33 extending upwardly alongside the inner surface of the glassWall. In a tube of the particular type illustrated, the envelopesections are fused together at a seal 34 in reduced portion 3. Our

shield 28 thus also protects this seal from heat originating at theelectrodes.

We claim:

1. An electronic tube comprising an envelope having a stem, a cathodeand. gridelectrode in the envelope, leads for the cathode sealed tothestem, a grid lead supporting the grid and sealed.

to the envelope intermediate the ends of the envelope, and a shieldmounted on the grid lead and interposed between the electrodesand saidstem.

2. An electronic tube comprising anenvelope having a stem at one endthereof, a plurality of A serious problem in thermionic tubes is toprevent leaks from developing at the mediate the ends thereof, and ashield mounted on the grid supporting means and disposed transversely ofsaid axis between the electrodes and said stem, said shield covering theends of all of said groups of electrodes.

3. An electronic tube comprising an envelope, electrodes extendinglongitudinally of the envelope, means supporting the electrodes in theenvelope, and a shield interposed between the electrodes and an end ofthe envelope, said shield extending transversely of said electrodes andbeing substantially co-extensive with that crosssectional area of theenvelope with the peripheral edge of the shield spaced from the envelopeside wall.

WILIIAM W. EITEL.

JACK A McCULLOUGI-I.

